Field of the Invention
The present invention generally relates to a surgical stapling instrument for applying surgical staples to tissue and, more particularly, to a surgical stapling instrument for performing a circular anastomosis stapling operation. More specifically, this invention relates to a surgical instrument in which a stapling head assembly is mounted by a flexible shaft to an actuator handle assembly and to an improved actuator mechanism for transmitting the required operating forces and movements from the actuator handle assembly through the flexible shaft to the stapling head assembly. Also, this invention relates to an improved stapling head assembly which reduces the operating forces required to perform the tissue stapling and cutting operations. Further, this invention concerns an improved actuator mechanism which controls the opening and closing of the stapling head assembly and adjustment of the anvil gap to produce a desired staple height.